Stethoscopes are used by physicians to listen to sounds produced in the human body, such as sounds from the lungs or the heart. A typical stethoscope has a chest piece, a tube, and ear pieces. The chest piece encloses a sound chamber and has a diaphragm. When placed against a patient, the diaphragm vibrates, thus creating sound in the sound chamber. The tube extends into the sound chamber and carries the sound to the ear pieces for the user to hear the sounds.
Some attempts have been made to improve the reception and expand the options of this typical stethoscope. Kazuma, U.S. Pat. No. 4,776,426, discloses a chest piece that is divided into two equally sized, semi-circular diaphragms and has two sound receiving chambers. Each chamber is separately coupled through a tube to one of the right and left ear tubes. This stethoscope purportedly provides stereophonic effect and more sensitive reception.
Hill, U.S. Pat. Nos. 4,270,627 and 4,387,784, discloses a stethoscope that has two resonant cavities and a switch for the user to select one or neither of these cavities. In these two patents, the resonant cavities are described as being designed to amplify a certain frequency range, while also venting pressure waves through openings into the ambient environment.